use std::sync::RwLock;
use std::collections::hash_map::HashMap;
use std::sync::Arc;

struct User {
    token: String,
}

struct MyStruct {
    users: RwLock<HashMap<String, Arc<RwLock<User>>>>
}

impl MyStruct {
    pub fn get_mut(&self, uid: &str) -> Option<Arc<RwLock<User>>>
    {
        if let Some(u) = self.users.read().unwrap().get(uid)
        {
            Some(u.clone())
        }
        else
        {
            None
        }
    }

    pub fn update_token(&self, uid: &str, token: &str)
    {
        if let Some(u) = self.get_mut(uid)
        {
            u.write().unwrap().token = token.to_string();
        }
    }
}

fn main() {
    let db = MyStruct {
        users: RwLock::new(HashMap::new())
    };
    db.users.write().unwrap().insert("test".to_string(), Arc::new(RwLock::new(User {token: "test".to_string()})));
    let user = db.get_mut("test").unwrap();
    db.users.write().unwrap().clear();
    user.write().unwrap().token = "36".to_string();
    println!("{}", db.get_mut("test").unwrap().read().unwrap().token);
}